1 #ifndef __LINUX_COMPILER_H 2 #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead." 3 #endif 4 5 /* 6 * Common definitions for all gcc versions go here. 7 */ 8 #define GCC_VERSION (__GNUC__ * 10000 \ 9 + __GNUC_MINOR__ * 100 \ 10 + __GNUC_PATCHLEVEL__) 11 12 13 /* Optimization barrier */ 14 /* The "volatile" is due to gcc bugs */ 15 #define barrier() __asm__ __volatile__("": : :"memory") 16 17 /* 18 * This macro obfuscates arithmetic on a variable address so that gcc 19 * shouldn't recognize the original var, and make assumptions about it. 20 * 21 * This is needed because the C standard makes it undefined to do 22 * pointer arithmetic on "objects" outside their boundaries and the 23 * gcc optimizers assume this is the case. In particular they 24 * assume such arithmetic does not wrap. 25 * 26 * A miscompilation has been observed because of this on PPC. 27 * To work around it we hide the relationship of the pointer and the object 28 * using this macro. 29 * 30 * Versions of the ppc64 compiler before 4.1 had a bug where use of 31 * RELOC_HIDE could trash r30. The bug can be worked around by changing 32 * the inline assembly constraint from =g to =r, in this particular 33 * case either is valid. 34 */ 35 #define RELOC_HIDE(ptr, off) \ 36 ({ unsigned long __ptr; \ 37 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ 38 (typeof(ptr)) (__ptr + (off)); }) 39 40 #ifdef __CHECKER__ 41 #define __must_be_array(arr) 0 42 #else 43 /* &a[0] degrades to a pointer: a different type from an array */ 44 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 45 #endif 46 47 /* 48 * Force always-inline if the user requests it so via the .config, 49 * or if gcc is too old: 50 */ 51 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ 52 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) 53 # define inline inline __attribute__((always_inline)) 54 # define __inline__ __inline__ __attribute__((always_inline)) 55 # define __inline __inline __attribute__((always_inline)) 56 #else 57 /* A lot of inline functions can cause havoc with function tracing */ 58 # define inline inline notrace 59 # define __inline__ __inline__ notrace 60 # define __inline __inline notrace 61 #endif 62 63 #define __deprecated __attribute__((deprecated)) 64 #define __packed __attribute__((packed)) 65 #define __weak __attribute__((weak)) 66 67 /* 68 * it doesn't make sense on ARM (currently the only user of __naked) to trace 69 * naked functions because then mcount is called without stack and frame pointer 70 * being set up and there is no chance to restore the lr register to the value 71 * before mcount was called. 72 * 73 * The asm() bodies of naked functions often depend on standard calling conventions, 74 * therefore they must be noinline and noclone. GCC 4.[56] currently fail to enforce 75 * this, so we must do so ourselves. See GCC PR44290. 76 */ 77 #define __naked __attribute__((naked)) noinline __noclone notrace 78 79 #define __noreturn __attribute__((noreturn)) 80 81 /* 82 * From the GCC manual: 83 * 84 * Many functions have no effects except the return value and their 85 * return value depends only on the parameters and/or global 86 * variables. Such a function can be subject to common subexpression 87 * elimination and loop optimization just as an arithmetic operator 88 * would be. 89 * [...] 90 */ 91 #define __pure __attribute__((pure)) 92 #define __aligned(x) __attribute__((aligned(x))) 93 #define __printf(a, b) __attribute__((format(printf, a, b))) 94 #define __scanf(a, b) __attribute__((format(scanf, a, b))) 95 #define noinline __attribute__((noinline)) 96 #define __attribute_const__ __attribute__((__const__)) 97 #define __maybe_unused __attribute__((unused)) 98 #define __always_unused __attribute__((unused)) 99 100 #define __gcc_header(x) #x 101 #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h) 102 #define gcc_header(x) _gcc_header(x) 103 #include gcc_header(__GNUC__) 104 105 #if !defined(__noclone) 106 #define __noclone /* not needed */ 107 #endif 108 109 /* 110 * A trick to suppress uninitialized variable warning without generating any 111 * code 112 */ 113 #define uninitialized_var(x) x = x 114 115 #define __always_inline inline __attribute__((always_inline)) 116